I am getting pretty concerned about my bleeding

Avery
I had my baby girl 7 weeks ago. I bleed for 4 weeks then spotted for a week and started my what I think is my period . It's two weeks into my period and I'm bleeding pretty heavy. I also am having blood clots. I've been getting light headed and I am super tired ( like that tired feeling you get before you start your period )  when should I be concerned ?